Complication with default_status

[jasonkarns]

I've run into a complication with the way handler's ::default_status is used.

Presumably, the "proper" way for a custom handler to derive and expose status codes is to override #status_code. Within this method, I was expecting to be able to:

1. return @status code if set (which would presumably mean the :status option was explicitly passed to register_exception
2. derive the status code from the exception class if not set.
3. fallback to the handler's ::default_status if the exception class didn't define its own status code

However, this line is causing issues:

rescue_registry/lib/rescue_registry/registry.rb

Line 31 in eea958f

status = options[:status] ||= handler.default_status

Because the handler's default_status is "forced" into the options hash, it is impossible for a custom handler to differentiate between an explicit status provided to register_exception from the handler's own default status used in place of the :status option.

I don't think I understand the rationale well enough to offer a PR with an alternative. (https://en.wikipedia.org/wiki/Wikipedia_talk:Chesterton%27s_fence) So discussing it here instead 😄

To work around this, I presently have some pretty hacky code:

class CustomHandler < RescueRegistry::ExceptionHandler
  # sentinel to distinguish explicit :status option from this default
  def self.default_status
    9000
  end

  # Let the exception tell us which status code it maps to
  def status_code
    # respect explicit :status option if provided
    return super if status < self.class.default_status

    # otherwise, derive from exception
    exception.status.presence || 500
  end

I'm hoping that it would be possible to eliminate the status = options[:status] ||= handler.default_status and instead have ExceptionHandler's inherited implementation of status_code be @status.presence || self.class.default_status? That way subclasses which override status_code could distinguish an explicit :status (b/c @status would be non-nil); and still invoke super to get the default value if they wish?

I can open a PR to this effect unless there's some other known logic depending on the current behavior.

[wagenet]

Apologies for the delayed reply here.

First off, let me note that I'm a big fan of Chesterton so I approve of him being referenced :)

Unfortunately, it's been a while since I worked on this project so I'm not 100% sure that even I remember all of my rationale. It also looks like I didn't specifically test this, so that's less than ideal :/

One option might be to allow default_status to take an argument of the current exception, though I guess that might technically be a breaking change.